Very limited information is available concerning the biology and pathogenic determinants of Mycoplasma genitalium. This is a result of difficulties in their isolation from clinical samples; their highly fastidious nature; their slow growth rate; the absence of a portfolio of wild-type strains, mutants, genetic tools and realistic animal models for comparative study; and the fact that very few laboratories around the world investigate M. genitalium. Nonetheless, M. genitalium is considered a leading cause of chlamydial-negative, non-gonococcal urethritis based upon a range of epidemiologicat studies and PCR and serological criteria. Also, M. genitatium has been implicated in numerous other genitourinary and extragenitourinary tract pathologies. The goals proposed in this application focus on important and fundamental properties of this pathogenic mycoplasma, using a collection of early passage strains recently isolated from cervical and vaginal specimens of women attending the San Antonio Sexually Transmitted Diseases Clinic. The overall aims of this proposal are: (1) molecular typing of single-colony-cloned cervical and vaginal M. genitalium isolates based on evaluation of specific gene sequence diversity; (2) identification of M. genitalium-unique immunodominant P140 and P110 epitope-containing domains for diagnostic purposes; and (3) establishment and assessment of chronic, persistent M. genitalium infections in human target cells. These studies should assist in understanding how M. genitalium infections are accompanied by dynamic changes in specific gene sequences, which may influence detection and diagnostic properties, and how mycoplasmas parasitize and persist for extended periods of time, possibly circumventing immune surveillance and antibiotic therapies.